Temperature controlled device



1965 E. H. LUSEBRINK 3,201,558

TEMPERATURE CONTROLLED DEVICE Filed May 24, 1965 2 Sheets-Sheet 1 FIG.

INVENTOR ELMER HENRY LUSEBRINK BY flan 14 ATTORNEY Aug. 17, 1965 E. H.LUSEBRINK 3,201,558

TEMPERATURE CONTROLLED DEVICE Filed May 24, 1963 2 Sheets-Sheet 2 F|G.3F|G.4

200 I90 F|G.5 55 5 nnnnnnnnn LUUUUUUUU F|G.6 LI"! A IMFD 62 ll A I 220vLI 2m L4 220v 3 0 L v A R2 I01:-

INVENTOR ELMER HENRY LUSEBRINK ATTORNEY United States Patent f 3,201,553TEMRERATURE CONTRULLED DEVICE Elmer Henry Lusehrink, New Shrewsbury,N.J., assignor to E. 1. du Pont de Nemours and Company, Wilmington, DeL,a corporation of Delaware Filed May 24, 1963, Ser. No. 283,078 '7Claims. (Cl. 219-10131) This invention relates to a temperaturecontrolled device for thermally treating moving webs.

Heated rolls and rollers are widely used in a number of different webprocessing machines in a variety of industrial applications. Forexample, many calendering and laminating operations, treatments oftextiles, drying of paper webs, etc., rely on the use of heated rolls.Generally, these rolls are of considerable mass and are designed tomaintain a certain elevated temperature over a long period of time toafford a uniform treatment of a web of great length. Such rolls areusually heated internally by means of steam or electricity. Inapplications where repeated short, intermittent, thermal web treatmentsof only a few seconds duration are required, such rolls do not performsatisfactorily. They require relatively long heat-up times and, becauseof their mass and heat capacity they maintain the elevated temperaturefor a considerable length of time after the heating means isdeactivated.

It is an object of this invention to provide an improved deviceembodying web processing rollers having rapidheating characteristics. Itis a further object to provide a device with such rollers that have alow heat capacity and will cool rapidly when the heating means isde-energized. Another object is to provide rollers that maintain adesired temperature within a narrow limit. A still further object is toprovide rollers that can go through a succession of short hot and coldcycles. Another object is to provide such rollers that have minimumdeflection under a uniform load and have a hard, smooth surface.

Yet another object is to provide a device embodying such rollers thatare inexpensive, operate on normally supplied electric current, are easyto manufacture, and require no maintenance.

The temperature controlled device of this invention comprises, incombination,

(a) A laminated core of high magnetic permeability having a cylindricalsection,

(b) A frame for supporting said core,

(c) An electrically conducting coil connected to a source of alternatingcurrent and surrounding a portion vniovement of the free end of theroller.

The device of the invention is particularly useful in ofiice copymachines of the photothermographic type in which an image of an originalis produced on a receptor sheet by performing a thermal transferoperation from a selectively photopolymerized matrix material. Machinesof this type are disclosed in assignees copending patent applicationsHeiart and Velvel, Ser. No. 234,616, filed Nov. 1, 1962, and Cohen, Ser.No. 250,856, filed Ian. 11, 1963. In these machines the thermal processroller 18 mounted so that it is rotatable only when it is in contactwith the moving matrix and a rotating pressure roller.

3.,2111558 Patented Aug. 1?, 1965 Suitable photopolymerizable matrixmaterials for use in such machines are disclosed in U.S. patent, Burgand Cohen, 3,060,023, issued Oct. 23, 1962, and U.S. patentapplications, Burg and Cohen, Ser. No. 163,078, filed Dec. 29, 1961;Heiart, Ser. No. 123,651, filed July 13, 1961; Cohen and Luebbe, Ser.No. 156,518, filed Dec. 1, 1961; and Burg, Ser. No. 234,214 filed Oct.30, 1962.

The invention is best explained by means of the attached drawings whichare part of this specification and in which:

FIG. 1 is a front elevation of a temperature controlled device of theinvention in combination with a pressure roller;

FIG. 2 is a front elevation with parts of the ends in section of theprocess roll and showing the primary windings;

FIG. 3 is a left end elevation of the device.

FIG. 4 is a right end elevation of the device.

FIG. 5 is a plan view of an alternative form of the invention using anO-shaped core and without a support ing frame; and

FIG. 6 is a wiring diagram for a suitable temperature control circuit.

Referring now to FIGS. 1 and 2, the temperature controlled devicecomprises a tubular metal roller 11 of low heat capacity, e.g., copper,having integral end flanges 12, which roller surrounds and rotates abouta section of a fixed laminated iron core 13 and fixed primary coil 14wound around said core and intervening layer 15 of dielectric material,e.g., paper, mica or polyethylene terephthalate. The tubular copper rollserves as a shorted secondary turn on a transformer and also functionsas a heating roller. The laminated iron core acts both as a support forthe roller and as a conductor of magnetic flux. The core is supported byan outer frame 16 having depending spaced legs 17 and central arms 18which support the ends of the core. The frame is made of a metal ormetal alloy of high magnetic permeability so as to provide a good fluxpath between the poles of the iron core.

The primary coil 14- .is energized from a suitable power line and sincethe windings do not rotate, the power leads can be inserted throughsuitable holes (not shown) drilled through the insulating bearing blocks19 that fit into the ends of the roller 11. These bearing blocks arefastened to the core, e.g., they have a light press-fit and the rollerrotates on the outer bearing surface of the bearing blocks; also, theseblocks radially support the roller. The roller can also move lengthwiserelative to the core to compensate for diiferential roller-to-coreelongation. Surrounding the bearing blocks 19 are coacting thrustcollers 2d the vertical walls of which act as thrust bearing surfacesagainst which the flanges of the roller press. These bearing blocks andthrust collars are preferably made of dielectric material, e.g., a resinor superpolymer, such as tetrafluoroethylene resin, polystyrene orpolymethylmethacrylate.

One end of the core is anchored by means of pins 21 to arm 13. Theright-hand thrust collar presses against the inner surface of this armas a base point for determining elongation of the metal rolier due totemperature increase. The other end of the roller 11 is free to move orelongate laterally due to thermal expansion. The unconstrained end ofthe roller presses against the thrust collar on the left end of thedevice. A yoke 22 surrounds the latter thrust collar and is fastenedthereto by means of clevis pins 23, extending through suitable holes(not numbered) near the outer ends of the arms of the yoke. The leg 24-of the yoke pivots about shaft 25 which extends across a suitable slot(not shown) in the frame member. The lower end of the leg of the yokehas attached thereto a suitable pin 26 which, in turn, is pivotallyconnected to a suitable switch 27. The other end of this switch isconnected to an adjusting screw 28 the initial current.

. 2% that extends through a suitable threaded opening (not numbered)near the bottom of depending central bracket 29 of the main frame 316.

Switch 27 is a displacement type switch and the movement of the yoke andthe legthereof mechanically amplifies the movement of the switch. Thisswitch has 'contact points 3b which contact and separate in response tomovement of the leg of the yoke, which in turn is controlled by thermalexpansion of the tubular roller 11. These contact points are connectedby means of suitable electric wires of the electrical control circuit.

In the embodiment of the invention shown in FIGS. 1, 3 and 4, the heatedroller is normally rotated by contact with rotating pressure roller 31which has shaft extensions 32 that are journalled in suitable bearing inthe arms of the frame member. The shaft extension on the right end ofthe pressure roller can be journalled directly in the frame arm as shownin FIG. 4. However, as shown in FIG. 3, the shaft extension on the leftend of the pressure roller is preferably journalled in a separate arm 33which is fastened to the main arm by means .of bolts 34 extendingthrough holes (not numbered) in .lateral flanges on said arm. Thesebolts have threaded adjustment with the main arm of the frame.Alternatively, a gear or pulley could be mounted on the roller androtated by a gear, or a pulley and a belt drive. Also, the core, primaryand roller can be made rotatable, the

= core serving as the axle. A driving means could be con- .The laminatediron core 13 is O-shaped and is of the .closed core type. being withinthe tubular roller, are wound on one side The primary windings, insteadof of the core. The metal roller 11, however, constitutes a shortedsecondary member of the device. This tubular roller revolves about theother section of the O-shaped 'member as shown in FIG. 5. Antithrustbearing 20-11 is used between bearing block 19-a and member 20.

FIG. 6 shows a suitable electric circuit for the temperature controlleddevice described above. SW is the main power switch and upon turn-on thepower flows through Tsw into the primary windings on the core L and LThe windings are placed in parallel to increase After the rollertemperature rises and the roller elongates to the set point, thedisplacement switch Tsw (27 in FIG. 1) opens. When this occurs, relay Apicks up and holds itself in through contacts A and condenser Cwhereupon contacts A and A transfer windings L and L into series, thusreducing the .amount of current in the primary during successive heat-modulation cycles.

R C and R C are arc-quenching means and they are used to protect therelay contacts. The displacement switch acts to maintain the temperatureat the set point. When the main power switch SW is opened, relay A dropsout and the circuit is re-set to parallel connections between L and LThe circuit diagram shows typical values of the various components.

During normal operation of the temperature controlled device of theinvention, when switch SW is closed the power flows through the parallelwindings in the primary causing an alternating magnetic flux to flowthrough the core. This flux induces an in the shorted secondary, andeddy currents quickly heat the roll surface. The

heat created causes thermal expansion of the roll resulting in itselongation.

140 volts.

-has good thermal conductivity, a low specific heat, and

low electrical resistivity. However, silver alloy or aluminum rollers,because of their physical qualities, can also be used. The outer surfaceof the roller can be plated with an appropriate meta-l, such aschromium, to provide a harder and reflective surface. The inside surfacecan be heat insulated or chrome plated to reduce the heat loss to theprimary windings and the iron core. The inside diameter of the coppertubing should be such that only a small space or void 36 exists betweenthe primary winding and the roller. The space should only be so large asto allow the roller to turn around the windings and act as an insulatorbetween the heat produced in the roller and the windings and the core.The closer the tubular roller is to the windings, the better will be thecoupling coefiicient, minimizing reactive transformer loss.

In the preferred embodiment, two bearing systems were used, one to allowthe roller to rotate and the other to allow the roller to movelengthwise relative to the transformer 'core. 'These solid bearingblocks are made of anti-friction, dielectric materials, as describedabove. Other bearing combinations that provide for the necessarymovements will be obvious to those skilled in the art. For example, theiron core, primary windings, and -the copper roll could be maderotatable by using slip rings to supply the power to the windings.

The preferred temperature control means is based on the elongation ofthe roller due to the heat produced in it. The elongation of the rolleris transmitted by the .linkage to the displacement switch. This switchmechanically amplifies the elongation and when the elongation reaches aset limit, the switch is tripped. The tripping of the switch regulatesthe flow of the power to the primary windings. There are several typesof displacement switches that may be used, such as the Thermoswitch,manufactured by the Fenwal Co., Ashland, Mass, or the Sternco #H-7F,manufactured by the Stevens Manufacturing Co., Mansfield, Ohio.

These displacement switches use the same basic principle. A slightmovement, such as that caused by thermal elongation, is transmitted tothe switch, which mechanically amplifies the movement. In the switchmade by the Fenwal Co., this is accomplished by means of a double 5cotangent yoke, and when a set displacement is reached the switch isopened. With the Thermoswitch switch, one end may be attached to thelinkage and the other end is attached to the frame. A Vernier adjustmentattaches the one end to the frame and is used to set the switch-for thedesired displacement. This switch will open and close contacts with adifferential displacement of approximately 20 10- inches. With a rollertemperature of C. as the set point, this switch maintains thetemperature within :1" C. (125 roller temperature) with an input voltagechange of from 30 to Other type temperature control means can be used,but most contacting type sensing devices such as thermocouples andthermistors cannot accurately follow the rapid rate of the rollertemperature rise without overshoot. If an O-shaped core is used, thetemperature control means could be an air gap 35. The air gap is shapedto fit the magnetic and thermal parameters of the device in use in sucha manner that just enough flux is induced in the secondary to match theheat load in the roller producing thermal equilibrium. Some of theparameters involved are the permeability of the core material, the rateof temperature rise in the roller, the thermal coeflicient of expansionof the copper roller, and the desired temperature set point.

This gap can be spring loaded and will normally be closed when theroller is cold. When it is closed, there will be maximum core fluxtransmission. As the roller heats, lineal expansion forces the core gapopen and the core flux and coupling is reduced. With this type oftemperature control, the transformer primary must swing, i.e., it mustoffer low impedence to a heavy load and oifer high impedence to a lightload. If a proper relationship between the roller elongation and the gapopening is obtained, the roller Will remain at a desired temperaturewhen the temperature control point and the input energy rate arecomplementary; thus the assembly can be self-controlling. This type ofdevice has an obvious advantage of having a continuous input power,modulated by thermal demand.

A typical roller of the type shown in FIGS. 1 and 2, having a rollerlength of ten inches, composed of one inch inside diameter copper tubingwith a wall thickness of 0.025 attained a temperature of 125 C. from acold start (25 C.) in seven seconds, requiring an input of 110 v. at 8amperes.

The process roller of this invention can be varied as to its size, butto have high performance an optimum relationship of at least fourrelated parameters should be obtained, i.e., the dimensions of theheated roller, the physical properties of the heated roller, thetransformer characetr-istics, and the characteristics of the temperaturecontroller.

The process roller device of this invention has many advantages over theprior art. The rollers are rapid-heating and self-regulating. They arerelatively inexpensive, but highly eificient. The control circuitry issimple, small, of low weight, and can be adapted easily to smallequipment. The roller device can handle webs of any length, singlesheets or rolls. The temperature is controlled according to the demand,so that heating cycles of a few seconds or of any longer time can bemaintained.

Iclairn:

1. A temperature controlled device for thermally treating a sheetcomprising in combination (a) a core of high magnetic permeabilityhaving a cylindrical section,

(b) a frame for supporting said core,

(c) an electrically conducting coil connected to a source of alternatingcurrent and surrounding a portion of said core,

(d) a tubular metal roller having a high coefiicient of expansion, goodthermal conductivity, low specific heat and low electrical resistivitysurrounding the cylindrical section of the core and journalled on spacedinsulating bearing blocks mounted on said core,

(e) one end of said roller being restrained from axial movement and theother being free to move axially, and

( f) a switch in the electrical circuit for the coil for energizing anddeenergizing the coil in response to axial movement of the free end ofsaid roller.

2. A device according to claim "-1 wherein said tubular roller surroundssaid coil.

3. A device according to claim 1 wherein said coil is disposed on aportion of said core that is not surrounded by the roller.

4. A device according to claim 1 wherein said roller is composed ofcopper;

S. A device according to claim 1 wherein said roller is composed ofcopper having a chromium plated inner and outer surfaw.

6. A device according to claim 1 wherein said roller is composed ofaluminum.

7. A device according to claim 1 wherein said core is laminated.

References Cited by the Examiner UNITED STATES PATENTS 2,27 3,423 2/42Somes 21910.49

References Cited by the Applicant UNITED STATES PATENTS Re.23,619 2/ 5 3Weller. 2,301,589 11/42 Shepard. 2,541,416 2/51 Harrison. 2,643,475 6/53Klopfenstein.

RICHARD M. WOOD, Primary Examiner.

1. A TEMPERATURE CONTROLLED DEVICE FOR THERMALLY TREATING A SHEETCOMPRISING IN COMBINATION (A) A CORE OF HIGH MAGNETIC PERMEABILITYHAVING A CYLINDRICAL SECTION, (B) A FRAME FOR SUPPORTING SAID CORE, (C)AN ELECTRICALLY CONDUCTING COIL CONNECTED TO A SOURCE OF ALTERNATINGCURRENT AND SURROUNDING A PORTION OF SAID CORE, (D) A TUBULAR METALROLLER HAVING A HIGH COEFFICIENT OF EXPANSION, GOOD THERMAL CONDUCTIITY,LOW SPECIFIC HEAT AND LOW ELECTRICAL RESISTIVITY SURROUNDING THECYLINDRICAL SECTION OF THE CORE AND JOURNALLED ON SPACED INSULATINGBEARING BLOCKS MOUNTED ON SAID CORE, (E) ONE END OF SAID ROLLER, BEINGRESTRAINED FROM AXIAL MOVEMENT AND THE OTHER BEING FREE TO MOVE AXIALLY,AND (F) A SWITCH IN THE ELECTRICAL CIRCUIT FOR THE COIL FOR ENERGIZINGAND DEENERGIZING THE COIL IN RESPONSE TO AXIAL MOVEMENT OF THE FREE ENDOF SAID ROLLER.